NASA, along with other international space agencies, seem to be pretty good at putting things into Earth’s orbit, but they are not so good when it comes to bringing things down. As a result, Earth’s orbit has been cluttered with space junk which has put other spacecraft, include those which are manned, in danger of a possible catastrophic collision. The solution may be in the form of technology called a solar sail.

A solar sail is a form of spacecraft propulsion system which uses radiation pressure, which can come from a star like our own Sun, or from an artificial source like a laser. It also has the ability to act as a parking brake to slow down spacecraft for de-orbit by skimming the top of our atmosphere.

Such technology has been successfully tested by NASA this month on board a small spacecraft called NanoSail-D. At first, NASA believed the mission was a failure before it even began. That’s because the small spacecraft was stuck inside its mothership called the Fast, Affordable, Science and Technology SATellite (FASTSAT), which was launched in November. Luckily, and for an unknown reason, the NanoSail-D spacecraft ejected from its mothership on January 17. A few days later, on January 20, the NanoSail-D unfurled its solar sail. The sail consists of a thin polymer sheet of reflective material which covers a 10 m2 area.

The solar sail will provide enough aerodynamic drag to allow the NanoSail-D to de-orbit within 70 to 120 days. This will test the possibility of including solar sails on future NASA satellites to allow them to return to Earth and harmlessly disintegrate in the atmosphere. Such a technique could prevent the build-up of future space junk. Of course, a solar sail does have an accelerator pedal in addition to a brake which is why NASA engineers will be measuring the pressure of sunlight on the sail as well.